Up to now, as the configuration of an internal optical system of a color liquid crystal projector, there are employed the horizontal type unit and the vertical type unit. Each of a projector 200a being of the horizontal type shown in FIG. 1A and a projector 200b being of the vertical type shown in FIG. 1B color-separates white light emitted from a light source, not shown, into three primary colors of red, green and blue using a dichroic mirror 201, and modulates thus color-separated lights in accordance with image signals using three liquid crystal panels, and color-composites thus modulated lights, and extendedly projects thus composited light to a screen using a projection lens 202 to display an image.
Here, when the size of an image to be projected I is H×V, being subject to the disposition of a dichroic mirror 201 shown in FIGS. 1A and 1B, the horizontal type projector 200a has the depth and width of its housing determined depending on the horizontal dimension H of the image to be projected I, and the vertical type projector 200b has the depth and height of its housing determined depending on the vertical dimension V. Since the horizontal length is longer than the vertical length as for a liquid crystal panel, the horizontal type projector 200a has a larger optical system for separating/compositing white light emitted from a light source as compared with the vertical type projector 200b, which undesirably leads to cost increase. In particular, in the case of using a liquid crystal panel with the aspect ratio of 16:9, etc. (a wide panel), which is suitable for video image projection, even though the length of the diagonal line is equal to that of a liquid crystal panel with the aspect ratio of 4:3 which is suitable for data projection, the length of long side direction becomes longer, thereby the problem described above becomes further noticeable.
Meanwhile, as for a projector unit, it is important to make the size smaller and also to satisfy variation of dispositions such as hanging a projector from a ceiling, placing a projector on a floor, etc. In case a vertical type optical system is employed to make the unit size smaller, the size along the height direction becomes large, which makes it difficult to hang a projector from ceiling. Conversely, in case a horizontal type optical system is employed, even though variation of dispositions is increased, when a liquid crystal panel of the same size is used, the unit size becomes larger as compared with the case employing a vertical type optical system. This problem is particularly noticeable when employing a crystal liquid panel with the aspect ratio of 16:9, etc. (a wide panel) as described above.
Thus, since both conventional projectors of the vertical type and of the horizontal type respectively have advantage and disadvantages, it is not satisfactorily convenient to employ any types of unit.